Today, insulating glass units have achieved widespread use as building components. In order to produce insulating glass units inexpensively and in high volume, the use of mechanized and/or automated assembly methods is desirable. An insulating glass unit may include, for example, a pair of panes and a spacing frame interposed between the panes. The panes and the spacing frame together define the sealed space. In some applications, a gas is disposed in the sealed space of the insulating glass unit.
In many applications, the panes of the insulating glass unit are transparent. When this is the case, the insulating glass unit may form a portion of a window. Windows allow the occupants of buildings to view the world outside while allowing sunlight to enter the interior of the building. Sunlight is a natural antidepressant and helps the human body produce vitamin D thus, a certain amount of sunlight is essential to mental and physical well being.
When the panes of the glass unit are transparent, it is desirable to keep the inside surfaces of the panes free from visible defects and contamination. One example of a visual defect occurs when particles are present in the sealed space and settle on the inside surfaces of the panes. A second example of a visual defect occurs when materials disposed within the sealed space out gas resulting in visible discolorations on or in the panes. A third example of a visual defect occurs when the gas in the sealed space contains moisture which condenses on the inside surfaces of the panes.